Graphene is a new material with superb physical and electrical characteristics and has been considered the most notable material in the future. Several manufacturing techniques for graphene have been reported, such as Mechanical Exfoliation, Chemical Exfoliation, Exfoliation-Reintercalation-Expansion, Chemical Vapor Deposition, Epitaxy Synthesis, Chemical Synthesis, and so forth.
The mechanical exfoliation technique allows graphene to show its own excellent characteristics, but its final yield is extremely low, so this technique has been used in labs just for the studies on properties of graphene.
Although it has been reported that graphene manufactured by chemical vapor deposition has superb characteristics, this technique has some disadvantages, such as the use of heavy metal catalysts, complicated processes and its poor economic efficiency, thereby being restricted from being in the mass production of graphene.
The epitaxy synthesis technique has disadvantages in that the electrical property of the produced graphene is not good enough and the substrate is very expensive.
Accordingly, the most commonly used method for manufacturing graphene includes the steps of producing oxidized graphite by a chemical method, obtaining oxidized graphene via ultrasonic treatments, and deoxidizing the oxidized graphene to form graphene. Since the oxidized graphite produced in the above-mentioned method is, however, on the whole functionalized, it is likely to show lower physical and electrical characteristics. In addition, it is difficult to estimate that by which functional groups and how much the oxidized graphite will be functionalized. Thus, the estimation for the second-order reaction becomes also very difficult. As a result, finally produced graphene tends to lose its characteristic properties, so that the graphene manufactured using the oxidized graphite is strongly retrained from being used in various application fields, such as transparent electrodes, etc.